Lack of motivation is considered a hallmark of ADHD, a disease that affects 1 in 20 Australians. Now, a study from Monash University researchers has found that this low motivation is actually an avoidance of effort, both mental and physical.
In a world first, the study shows that addressing motivation and effort avoidance is an important aspect in treating the disease, and importantly, the study has revealed how prescription amphetamines, a common treatment for ADHD, can boost motivation and effort.
The study, led by Associate Professor Trevor Chong, from the Turner Institute for Brain and Mental Health and Monash School of Psychological Sciences, and published in the Journal of Neuroscience, is the first to study people with attention-deficit/hyperactivity disorder or ADHD's sensitivity to effort, and how medication can ameliorate that.
The study found that:
- individuals with ADHD had lower motivation to invest effort in both cognitive and physical tasks; and
- amphetamine increased motivation in cognitive and physical tasks to levels similar to that of healthy controls.
According to Associate Professor Chong, a long-standing assumption in the ADHD literature is that ADHD is associated with lower levels of motivation, particularly for cognitive effort. "Until now, no study has explicitly tested the proposition that ADHD is associated with lower motivation to invest cognitive effort, and very few have examined the motivation to invest physical effort in this population," he said.
"Our study provides the first evidence that cognitive motivation is indeed lower in individuals with ADHD than those without, and that this is also accompanied by a lower willingness to invest physical effort."
He added that "our data reassuringly shows that medications that are commonly used to treat ADHD are effective in improving motivation to level similar to those who do not have the condition
The research team tested 20 individuals with ADHD (11 males, 9 females) who were managed with amphetamine-based medication and 24 controls (8 males, 16 females).
The participants with ADHD were then tested when they were off medication and when they were on their medication, in an effort-based decision-making task, in which they were required to choose how much cognitive or physical effort they were willing to engage in return for reward.
